低共熔溶剂提取荔枝壳中的原花青素及其抗氧化活性

Extraction of Litchi Pericarp Procyanidins Using Deep Eutectic Solvents and Their Antioxidant Activity

摘要:

该研究通过建立低共熔溶剂(DES)最佳提取工艺为荔枝壳原花青素的绿色高效制备提供技术支撑。通过比较了4种低共熔溶剂与70%（V/V）乙醇提取对荔枝壳原花青素提取效率、化学构成及ORAC抗氧化活性的影 响，确定氯化胆碱-1,3-丁二醇为最佳提取溶剂。HPLC分析表明4种低共熔溶剂与70%（V/V）乙醇提取的荔枝壳 原花青素主要成分均为原花青素A2、芦丁、表儿茶素、原花青素B1及山奈酚-3-O-芸香糖苷。进一步通过单因素试验结合正交优化确定了氯化胆碱-1,3-丁二醇提取最佳工艺条件：料液比1:20（g/mL），溶剂摩尔比1:4，溶剂含水量50%（V/V），提取温度60 ℃，提取时间90 min，在该条件下提取液中的荔枝壳原花青素含量高达5.07 mg PE/mL，是70%（V/V）乙醇提取的1.4倍,其ORAC值及DPPH和ABTS+ 自由基的IC50值分别为5 496.25 μmol TE/mL、27.35 μg PE/mL和23.82 μg PE/mL，均优于70%（V/V）乙醇提取的原花青素（3 370.17 μmol TE/mL、36.41 μg PE/mL和31.56 μg PE/mL）（P<0.05），研究结果表明低共熔溶剂在荔枝壳原花青素提取方面具有显著优势。

Abstract:

The optimal process for litchi pericarp procyanidin extraction using deep eutectic solvents (DESs) was established to provide technical support for the efficient green preparation of litchi pericarp procyanidins. Litchi pericarp procyanidins were extracted using four DES types and 70% (V/V) ethanol to investigate and compare the extraction efficiency and the chemical composition and antioxidant activity (oxygen radical absorbance capacity) of the obtained procyanidins. HPLC-DAD analysis revealed that two procyanidin compounds (procyanidin A2 and B1) and three flavonoids (rutin, epicatechin, and kaempferol-3-O-rutinoside) were present in the extracts acquired using the four DESs and ethanol. Choline chloride-1,3-butanediol was the best extractive solvent. Furthermore, single factor tests and orthogonal optimization suggested that the optimum extraction conditions for choline chloride-1,3-butanediol are as follows: a liquid ratio of 1:20 (g/mL), a solvent molar ratio of 1:4, a solvent water content of 50% (V/V), an extraction temperature of 60 ℃, and an extraction time of 90 min. Under these conditions, the total procyanidin content reached 5.07 mg PE/mL, which is 1.4-fold that extracted using 70% ethanol. The oxygen radical absorbance capacity values and the IC50 values of the DPPH and ABTS free radicals of the finished choline chloride-1,3-butanediol-extracted extract were 5 496.25 μmol TE/mL, 27.35 μg PE/mL, and 23.82 μg PE/mL, respectively. In short, these results indicate that DESs exert significant advantages in the extraction of litchi pericarp procyanidins.